A bicycle may be equipped with pneumatic tires. Characteristics of these pneumatic tires are dependent on the pressure contained within the tires. An optimal pressure for modern bicycle tires can range from slightly above to many times greater than atmospheric pressure. Variables including tire size, tire type, bicycle and rider weight, surface conditions, and riding style all affect an optimal tire pressure for a bicycle pneumatic tire. Size, weight, and packaging constraints on certain bicycle tires and tire assemblies can dictate significant pressure loss rates, making regular pressure measurement important even to maintain a fixed optimal pressure. Defects in, or damage to, tires or tire assemblies can cause slow pressure leaks that regular pressure measurement may identify before these leaks become problematic. Additionally, frequent pressure adjustments due to changing variables mean that a rider will benefit from convenient and accurate pressure measurement.
Traditionally the pressure within bicycle tires is measured using an external pressure gauge such as may be found on a floor-based tire pump. Such a gauge must be connected to the tire assembly to measure pressure and cannot measure the tire pressure while the bicycle is in use and the tire assembly is rotating. The use of such a gauge for the identification of leaks is not ideal as many of these leaks may begin from damage incurred while the bicycle is being ridden and thus when such an external device cannot detect them. The requirement of a separate or external pressure gauge, not designed to be a permanent or semi-permanent component of the bicycle, limits when a rider can make accurate pressure adjustments. For instance, a tire pressure may commonly be increased with a tire inflating device such as a pressurized cartridge inflator or a portable tire pump without a pressure gauge and may be decreased by selectively opening a tire valve. However, without a device for accurately measuring the tire pressure, there is limited utility to these pressure adjustment techniques in achieving an optimal tire pressure.